4 ms·
What would be the difference between this and an SSD-based keystore and an instance of memcached with as much RAM as was necessary to hold the whole dataset?
by AndrewDucker 8y ago
What would be the difference between this and an SSD-based keystore and an instance of memcached with as much RAM as was necessary to hold the whole dataset?
- tyingq 8y agoIt appears to pool RAM from many servers. That would allow pool sizes larger than what fits in a single physical server.
- anentropic 8y agosimilarly, you can have a memcached cluster
- beamatronic 8y agoAlso known as Couchbase
- Rafuino 8y agoHere's a slide from Dormando (memcached maintainer) who spoke recently at QCon SF. He created extstore, which lets you offload values to SSD and keep keys in memory. With all hits on different types of SSDs, he's seeing near all-DRAM performance in terms of throughput and latency. https://twitter.com/justincormack/status/1059540644245295105 https://twitter.com/justincormack/status/1059540644245295105 The NAND SSD (dark blue line) is still hitting good performance but at ~250K queries per second hits P99 latencies above 1ms (a typical SLA Netflix calls out for their own caching using extstore). The Optane SSD (light blue line) stays well below 1ms P99 latencies up to ~500K queries per second. DRAM alone can handle more throughput but by then you have to take into account what your network can handle.
- AndrewDucker 8y agoThank you, that's fascinating.